The participant included in this study was a member of the research team. Eligibility criteria included wireless internet access at home, being between the ages of 10 and 17 years, a medical diagnosis of CP, the ability to exercise using the arms, self-reported mobility disability, and a caregiver to support the study procedures of the child. The participant recruited for this study was a 17-year-old male with spastic diplegic CP. He had mild-to-moderate hemiparesis, intellectual disability, and ambulated independently (Gross Motor Function Classification System level II). He received regular botulinum toxin injections for the management of spasticity in his lower limbs.

The case study was not considered research by the university review board; thus, review and approval by the board was not required. As per university guidelines for case studies, written informed consent and assent were still obtained from the participant and their caregiver prior to participation. Study data were deidentified using alpha-numeric codes, and participation was confidential. No compensation was provided for participation. No artificial intelligence was used in any portion of the manuscript.

The participant came to the laboratory for a baseline data collection visit, participated in the 12-week intervention, and then came back to the laboratory for a post–data collection visit. Health outcomes were measured predata and postdata. On the postvisit, he conducted an evaluative exercise assessment for our third study purpose. The participant completed the intervention in May 2022. This case study informed the development of a pilot randomized controlled trial [21].

The intervention prescription included a 12-week SIT program. The SIT program included 3 sessions per week that each lasted 15‐25 minutes. Each SIT session included a warm-up followed by 30 repeated sequences of 4 seconds of all-out arm exercise and 30 seconds of rest (totaling 2 minutes of all-out exercise over the entire session), as well as a cooldown. Rest periods included active or passive recovery that progressed from 30 seconds in week 1 to as low as 16 seconds in week 7 of the program, guided by the participants’ needs. The exercise prescription was based on a previous SIT study [16]. Regarding specific movements, the warm-up primarily included low-intensity repetitive movements that were opposite to those used in the exercise sequence. For example, backward “arm jogging” (shoulder circles backward emphasizing the posterior deltoids) was a common warm-up movement, given that most exercise movements used the anterior deltoids. Exercise movements coincided with the theme of the exercise video. Movements included gross shoulder and elbow movements, such as climbing motions, rope swinging, lightsaber chopping, web shooting, and vertical and straight forward punching. Videos informed the viewer to mirror or modify the movements to what felt “good” to them (eg, use only arm). Videos included verbal cues to encourage high-intensity exercise through verbal cues: “Try your very best!” “Don’t hold back,” and “Use all of your energy.” Videos were based on age-appropriate themes, specifically, 3 popular fictional superhero genres: Spider-Man, Star Wars, and Super Mario. The videos included 2 actors, 1 disability exercise expert (BL), and 1 child with CP (LB; Figure 1).

Each session was guided by a video that was played from a cloud-based server (YouTube). The intervention used a web-based platform, Zoom (Zoom Communications Inc), to allow videoconference supervision by a research staff member who was stationed at the research laboratory. The participant wore a Garmin Vivosmart 3 activity monitor (Garmin), which was used for a gross approximation of heart rate during exercise. Periodically during exercise, the research staff member would ask the participant what their heart rate reading was on their activity monitor, as well as their rating of perceived exertion using a 0‐10 scale [22]. At the end of each session, the participant was asked to rate their perceived exertion to gauge fatigue from the session as a whole. If exertion was lower than a score of 7 for 3 consecutive sessions, resistance bands were to be introduced as a form of exercise progression. Resistance bands were added in the tenth week of the program. The participant was consistently asked to keep his diet and nutrition habits stable throughout the intervention period.

At the postvisit, the participant was provided with 20 minutes of rest after his graded exercise test, after which he underwent an exercise evaluation of the SIT program. For the evaluation, the participant was equipped with the portable metabolic cart and exercised along with one of the SIT videos taken from the later weeks of the program (ie, a video with less rest). The purpose of this was to assess whether arm SIT could elicit a high intensity of exercise. According to the American College of Sport Medicine guidelines for determining exercise intensity, low intensity is characterized as 57%‐63% of the age-predicted maximum heart rate, moderate as 64%‐76%, vigorous as 77%‐95%, and near maximal or maximal as ≥96%, respectively [23]. In addition to the American College of Sports Medicine guidelines, we utilized the Tanaka equation (208 – 0.7 × age) for live target heart rate zones during exercise [24]. For the evaluation, the participant was asked to rest for 5 minutes, perform a warm-up of 3 minutes, and then do 3 stages of arm SIT: 3 minutes with no resistance band, followed by a 1-minute rest period, 3 minutes with a low-grade resistance band and a 1-minute rest period, and then 3 minutes with a midgrade band. Oxygen consumption was measured continuously throughout the evaluation.

Adverse events were monitored and recorded during the supervised sessions by the exercise coach. Additionally, during each call, the participant was asked how they were feeling since their last session, with a specific focus on whether their shoulders or arms were too sore to begin exercise and whether they experienced any injuries or problems since their last session.

Outcome measures were obtained before and after the 12-week program (at weeks 0 and 13). The primary outcome of interest was cardiorespiratory fitness, indicated by peak oxygen consumption (pVO₂), which was measured by a portable metabolic cart (COSMED K5, COSMED) during a graded exercise test using an arm ergometer. The test increases in resistance, and the individual performs the exercise until they can no longer continue. Test values were expressed as milliliters per kilogram per minute (relative measure).

Cardiometabolic health measures included a dual-energy x-ray absorptiometry scan to evaluate body composition (total mass, total lean mass, percent lean tissue, and percent fat tissue), a dried blood spot test to evaluate the lipoprotein profile (triglycerides, cholesterol, and low-density and high-density lipoprotein), glucose and glycated hemoglobin A_1c tests, and body weight measurement using a scale. To evaluate safety, the research staff consistently monitored the participant for adverse events (eg, muscle soreness/injury, overexertion, and illness).

The participant completed all 36 prescribed exercise sessions (100% attendance) with no adverse events or problems. An exercise band was introduced in week 10 to maintain an increased level of exertion. Heart rate monitoring of exercise intensity did not work as planned and was not recorded during the sessions, despite being planned. The data did not appear accurate for two reasons: (1) the participant was taking medications that blunt heart rate and (2) there was a notable delay between stopping the exercise and the participant reporting the heart rate to the coach (primarily due to difficulty reading the small values on the wrist monitor because the participant had substantial visual impairment).

At baseline, the participant had a BMI of 31.4 kg/m² and dyslipidemia (high-density lipoprotein <40, elevated total cholesterol:high-density lipoprotein ratio; Table 1). The participant achieved a 33.6% increase in pVO₂ (14.6 to 19.5 mL/kg⁻¹/min^–1), a 37.8% improvement in blood triglycerides (82 to 51 mg/dL), and a 15.4% improvement in their total cholesterol to high-density lipoprotein ratio (6.5 to 5.5). Glucose and glycated hemoglobin A_1c remained stable (88% to 80% and 5.2% to 5.1%, respectively). Additionally, he had a 5.9% reduction in body weight (171 to 161 lbs), and a 9.6% reduction in total body fat (61.35 to 55.48 lbs) from the arms, legs, and trunk (14.9%, 9.6%, and 8.72% reduction, respectively).

Results for the exercise evaluation are shown in Figure 2. At rest, the participant had a pVO₂ of 6.53 (SD 1.6) mL/kg⁻¹/min⁻¹. During warm-up, he had a pVO₂ of 8.78 (SD 3.5) mL/kg ⁻¹/min⁻¹. In stage 1 (no band), he exercised at a moderate intensity of 61.8% of his pVO₂ (12.04/19.5 mL/kg⁻¹/min⁻¹). In stage 2 (low-grade resistance band), he exercised at a near-maximal intensity of 90.8% pVO₂ (17.71/19.5 mL/kg^–1/min^–1). In stage 3 (midgrade resistance band), he exercised at a near-maximal intensity of 90.8% pVO₂ (17.61/19.5 mL/kg^–1/min^–1) [19]. Visually, the participant was performing faster movements during stage 2 (low-grade band) than he was in stage 3 (midgrade band). The rating of perceived exertion was 3 for the warm-up, 7 for exercise with no resistance band, and 10 at the end of each band stage.